Method for detecting resistance of a photo resist layer

Abstract

The present disclosure provides a method for detecting resistance of a photo resist layer. The method includes: providing a silicon wafer and measuring a refractive index of a surface of the silicon wafer as an initial refractive index of the surface of the silicon wafer; forming photo resist layers with different thicknesses on the surface of the silicon wafer; performing ion-implantation on the photo resist layers by predetermined amounts; peeling off the photo resist layers from the surface of the silicon wafer; and testing the refractive indexes of different areas on the surface of the silicon wafer after the ion-implantation, on which the photo resist layers with different thicknesses are located and determining the resistance of the photo resist layers with different thicknesses in contrast to the initial refractive index before the ion-implantation.

What is claimed is: 
     
       1. A method for detecting resistance of photo resist layers, comprising steps of:
 providing a silicon wafer and measuring a refractive index of a surface of the silicon wafer as an initial refractive index of the surface of the silicon wafer; 
 forming the photo resist layers with different thicknesses on the surface of the silicon wafer; 
 performing ion-implantation on the photo resist layers by predetermined amounts; 
 peeling off the photo resist layers from the surface of the silicon wafer; and 
 testing refractive indexes of different areas on the surface of the silicon wafer after the ion-implantation, on which the photo resist layers with different thicknesses are located, and determining the resistance of the photo resist layers with different thicknesses in contrast to the initial refractive index before the ion-implantation, 
 wherein after the step of testing the refractive indexes of different areas on the surface of the silicon wafer after the ion-implantation, the method further comprises: 
 calculating differences between the refractive indexes of corresponding areas on the surface of the silicon wafer covered by the photo resist layers with different thicknesses after the ion-implantation and the initial refractive index before the ion-implantation, and if one of the differences has an absolute value range of 0-0.02, determining that the photo resist layer with a corresponding thickness is resistant sufficiently and efficiently and that such a corresponding thickness is an effective thickness of the photo resist layer. 
 
     
     
       2. The method according to  claim 1 , wherein the step of forming the photo resist layers with different thicknesses on the surface of the silicon wafer comprises:
 coating photo resist onto the surface of the silicon wafer to form the photo resist layers. 
 
     
     
       3. The method according to  claim 2 , wherein the step of forming the photo resist layers with different thicknesses on the surface of the silicon wafer further comprises:
 exposing the photo resist layers coated on the different areas on the surface of the silicon wafer for different exposure periods and developing them to form the photo resist layers with different thicknesses. 
 
     
     
       4. The method according to  claim 3 , wherein the step of forming the photo resist layers with different thicknesses on the surface of the silicon wafer further comprises:
 measuring the thicknesses of the photo resist layers on the different areas. 
 
     
     
       5. The method according to  claim 2 , wherein a pre-baking process for the silicon wafer is performed after coating the surface of the silicon wafer with photo resist. 
     
     
       6. The method according to  claim 5 , wherein the pre-baking process is performed at a temperature of 10-150° C. and for 10-300 seconds. 
     
     
       7. The method according to  claim 6 , wherein the pre-baking process is performed by low temperature heating provided by an infra-red oven. 
     
     
       8. The method according to  claim 1 , wherein the thicknesses of the photo resist layers change continuously in steps from a center of the surface of the silicon wafer to is an edge of the surface of the silicon wafer. 
     
     
       9. The method according to  claim 1 , wherein the predetermined amounts comprise predetermined energy and doses. 
     
     
       10. The method according to  claim 1 , wherein the refractive indexes of the surface of the silicon wafer before and after the ion-implantation are measured by ellipsometry. 
     
     
       11. The method according to  claim 10 , wherein the tests for the refractive indexes before the ion-implantation and after the ion-implantation have the same testing condition and environment. 
     
     
       12. The method according to  claim 1 , wherein the thickness corresponding to a minimum absolute value of the differences of the refractive indexes of the surface of the silicon wafer after the ion-implantation and before the ion-implantation is selected from all of the effective thicknesses of the photo resist layers as an optimum thickness of the photo resist layers. 
     
     
       13. The method according to  claim 1 , wherein if the absolute value of the difference of the refractive indexes is greater than 0.02, it is determined that the photo resist layer with the corresponding thickness fails to be efficiently resistant. 
     
     
       14. The method according to  claim 4 , wherein the thickness of the photo resist layers change continuously in steps from a center of the surface of the silicon wafer to an edge of the surface of the silicon wafer. 
     
     
       15. The method according to  claim 7 , wherein the thickness of the photo resist layers change continuously in steps from a center of the surface of the silicon wafer to an edge of the surface of the silicon wafer. 
     
     
       16. The method according to  claim 4 , wherein the refractive indexes of the surface of the silicon wafer before and after the ion-implantation are measured by ellipsometry. 
     
     
       17. The method according to  claim 7 , wherein the refractive indexes of the surface of the silicon wafer before and after the ion-implantation are measured by ellipsometry. 
     
     
       18. The method according to  claim 8 , wherein the refractive indexes of the surface of the silicon wafer before and after the ion-implantation are measured by ellipsometry. 
     
     
       19. The method according to  claim 9 , wherein the refractive indexes of the surface of the silicon wafer before and after the ion-implantation are measured by ellipsometry.